The Increment option value should be an integer. As explained in primaryComponent(Ideal,Ideal) the algorithm, given in Eisenbud-Huneke-Vasconcelos, Invent math, 110, 207-235 (1992), relies on top(I + P^m) for m sufficiently large. The algoritm begins with m = 1, and increases m by the value of the Incrementoption until m is sufficiently large. The default value is 1.
See also: